1. Field of the Invention
The present invention relates to therapeutic compositions, and particularly to dialysate compositions.
2. Description of the Related Art
When functioning correctly, the kidneys help the body maintain a normal internal environment called homeostasis. Kidneys help accomplish this normal balance by ridding the body of excess fluids and metabolic waste products (toxins) as well as maintaining precise levels of glucose and electrolytes. Kidney failure can be caused by multiple factors. However, regardless of why a person's kidneys fail, the failure results in the accumulation of excess fluid and toxic waste in that person's body. This uremic poisoning eventually causes death unless the waste material is removed by some artificial means. Hemodialysis is the most common therapeutic measure for a person whose kidneys no longer perform their blood purifying function. Another common type of dialysis is peritoneal dialysis (PD).
Dialysate is the fluid utilized in dialysis, where dialysate serves to ‘clean’ the blood of kidney failure patients. During hemodialysis, the patient's blood is circulated on one side of a membrane within a dialyzer (i.e., artificial kidney), while dialysate flows on the other side of the membrane. Since blood and dialysate are separated by a semipermeable membrane, movement of molecules can occur between the blood and dialysate. Although the membrane pores are too small to permit blood cells and proteins to leave the blood, the pores allow waste products to be transferred from the blood to the dialysate.
Peritoneal dialysis utilizes the patient's peritoneal membrane as a dialysis membrane. Upon instilling a volume of peritoneal dialysate into the peritoneal cavity, osmotic pressure and a diffusion gradient cause excess fluid and waste products to leave the blood by crossing the peritoneal membrane and accumulate in the peritoneal cavity containing the dialysis fluid. After a sufficient dwell time, the spent peritoneal dialysate together with the accumulated excess fluid and waste products are drained from the peritoneal cavity.
Today, virtually all dialysate for hemodialysis is made at the site of treatment (in a hemodialysis machine) by mixing (1) treated water, (2) an acid concentrate, and (3) a base concentrate. Because the base concentrate typically contains sodium bicarbonate as the primary basic material, dialysate made by mixing these ingredients is commonly known as bicarbonate dialysate. Bicarbonate dialysate is almost universally made in the hemodialysis machine, through the use of a “three-stream” proportionate pumping mechanism wherein the treated water, liquid ‘acid concentrate’ and liquid bicarbonate (base) concentrate are combined. One patient typically requires 120 liters or more of dialysate for a single hemodialysis treatment. Chronic kidney failure patients are treated 3 times per week, 52 weeks per year.
The concentrates are supplied to the dialysis clinic in two forms; the ‘acid concentrate’ is generally supplied as a liquid and the bicarbonate is shipped as a dry powder. The acid concentrate typically contains sodium chloride, calcium chloride, potassium chloride, magnesium chloride, dextrose and sufficient acid (acetic acid) for pH balance. The precise composition of the acid concentrate to be used in a specific dialysis session is determined by a doctor's prescription.
Prior to a patient's treatment session, a jug of liquid acid concentrate is obtained. Generally, this jug of concentrate is drawn from a larger tank or drum of the acid concentrate. A staff member of the dialysis clinic also prepares a jug of sodium bicarbonate concentrate by mixing a quantity of powdered sodium bicarbonate with a specific quantity of treated water. Separate concentrated solutions of ‘acid’ and bicarbonate are necessary because combining concentrated acid and base solutions would cause the precipitation of calcium and magnesium carbonates. After proper mixing, the final dialysate has the concentrations prescribed by the physician.
As noted, kidney failure patients accumulate excess fluids and normally excreted substances in their blood, most notably, blood urea nitrogen (BUN) and creatinine. In fact, the reduction in the blood levels of these two substances is generally used to gauge the efficiency and overall effectiveness of dialysis. Often the efficiency of dialysis can be compromised by a number of factors, one of which could be the blockage of dialyzer membrane pores by clotted blood.
Additionally, many kidney failure patients suffer from chronic acidosis because their kidneys are not able to remove acid. Traditionally, one of the several goals of hemodialysis treatment is the correction of acidosis by providing higher than normal amounts of bicarbonate in the dialysate to buffer the excess acid in the blood. However, despite infusing “extra” bicarbonate during hemodialysis, normal blood bicarbonate levels are not sustained in many patients between hemodialysis treatments.
Accordingly, there is a need in the art for improved dialysate formulations that increase the efficiency of the hemodialysis treatment. The present invention is directed to meeting this need and provides additional related advantages as disclosed herein.